PULMONARY CIRCULATION EVALUATION BEFORE CAVOPULMONARY CONNECTIONS - THE CAVOPULMONARY BYPASS

The outcome of Fontan-type procedures is dependent on several risk fac tors, among which pulmonary vascular resistances (PVRs) are an importa nt component. Preoperative calculation of PVR entails several potentia l sources of error, particularly in patients with pulmonary atresia or multiple sources of pulmonary blood now. In an attempt to develop a r eliable test that accurately assesses the hemodynamic patterns of the pulmonary vascular bed before a Fontan procedure, a simulation of Font an-type circulation was achieved in 13 patients by a partial cardiopul monary bypass between the main pulmonary artery and both venae cavae ( cavopulmonary bypass). During cavopulmonary bypass, pressures and resi stances were recorded. Immediately after cavopulmonary bypass, the cir culation was converted to standard cardiopulmonary bypass and the cavo pulmonary connection was carried out. Preoperative pulmonary vascular resistance indexes were assessed toughly by the arteriovenous oxygen d ifference in systemic and pulmonary beds. There was no correlation bet ween preoperative and perioperative calculations of pulmonary vascular resistance indexes (r = 0.24; p = not significant). Hemodynamic data available for all patients then were correlated to the early postopera tive outcome assessed by a subjective four-point scale. A positive, si gnificant correlation was found with intraoperative PVR (r = 0.90; p < 0.001), indexed PVR (r = 0.90; p < 0.001), and the pulmonary to syste mic vascular resistance ratio (r = 0.98; p < 0.0001). Two of 13 patien ts had a 4-mm fenestration in the atrial baffle. No mortality or morbi dity was related to the procedure. The absolute values of PVR and pulm onary vascular resistance indexes were strikingly higher than generall y admitted for this type of procedure. Although establishment of nomog rams for decision-making would necessitate a larger prospective study, we conclude that the cavopulmonary bypass may be a useful adjunct to catheterization in borderline multipalliated patients who are candidat es for the Fontan operation.